Position and anatomical landmarks
The patient lies in the prone position on the operating table with a pillow under the abdomen to flatten the lumbar lordosis. Prior to the procedure, a lumbar spinal or epidural can be considered in order to decrease the discomfort caused by the puncture. Alternatively, the deep paraspinal muscles can be anaesthetised with local anaesthetics.
The C-arm is positioned in such a way that the promontory or waist of the vertebral body of L5 is visible using tunnel vision from the insertion point 5-7 cm lateral to the midline at the level of L4 (Figure 1). The C-arm must be rotated ± 45° both in an anterior posterior and a cranial direction.
After sterile preparation of the area, a 15 cm 20 or 22-G needle is positioned by means of fluoroscopy (tunnel vision) at the front of the intervertebral space of L5/S1. It is important to aspirate in order to avoid injection into the iliac blood vessels. From an anterior posterior view, the tip of the needle must be paravertebral at the level of the intervertebral space of L5/S1. From a lateral view, the tip of the needle must be at the anterior border of the vertebra of L5/S1.
Figure 1. Needle position in hypogastric plexus block: AP view.
In order to confirm the needle position and to avoid intravascular injection, it is wise to inject a contrast agent. The contrast agent should not spread beyond the lateral borders of the vertebral body of L5 or in a dorsal direction towards the nerve roots (Figure 2 and 3).
For hypogastric plexus test block procedures, 6-8 ml bupivacaine 0.25-0.5% can be used.
Figure 2. Needle position in hypogastric plexus block: oblique view with contrast.
For therapeutic purposes, 6-8 ml 10 % phenol in telebrix solution injected at each side of the vertebra can be used. Fractionated injection, using continuous fluoroscopy control of the contrast spreading, will increase the safety of the procedure.
Figure 3. Needle position in hypogastric plexus block: lateral view with contrast.
- Neurolysis of somatic nerves.
- Intravascular injection of neurolytic solution.
- In bilateral hypogastric superior plexus block, male sexual dysfunction can occur.